Is increased chemical complexity of extracellular polymeric substances (EPS) related to increasing salinity in polar sea ice?

Sea ice is found in frozen polar seas and covers approximately 13% of the Earth's surface. As seawater freezes, the salt present in the water becomes concentrated as brines within channels in the sea ice. These brine channels provide a habitat for a host of organisms, particularly single celled algae. Their biological activity results in high amounts of dissolved organic matter being produced in the brine channels, and both this material and the cells themselves are available as a food resource for other organisms. It has been found that the dissolved organic compounds in sea ice consist primarily of large polysaccharide molecules forming slimes or gels. This material is called EPS (extracellular polymeric substances). EPS are important because they can modify the environment surrounding a cell. It is throught that sea ice EPS help prevent freezing damage and exclude the high concentrations salts solutions which would otherwise damage cells. In this proposal, we will analyse the chemical composition of EPS taken from various sea ice samples collected during 2004-05 in the Antarctic ocean. It is expected that algal will make more complex EPS as the salt concentrations in the brine increase. These samples will allow us to determine whether the chemical composition of EPS does changes as the salinity increases, and what those chemical changes are. This information with help scientists understand how cells survive in harsh conditions and understand how EPS structure can be modified to provide useful environmental protection. These results will also be interesting to scientists working in other environments, where cells are stressed and wrap themselves in EPS.